Chemical structure of quinizarin. The arrow shows the definition of the molecular coordinate for dipole moments discussed in this paper.
Possible optical pathways that generate the low-frequency vibrational coherence upon IR excitation of the OH-stretching mode. (a) Coherent excitation to the levels. [(b) and (c)] Impulsive Raman processes in the level via different intermediate states.
(a) Solid line: infrared absorption spectrum of quinizarin in (, 0.2 mm cell). The arrows indicate the intensity axes for the two different wavenumber regions. Solvent contribution was subtracted. Dashed line: mid-IR pump spectrum. (b) Solid line: UV-visible absorption spectrum of quinizarin in . Dashed line: visible probe spectra at 546 and 565 nm.
Transient absorbance change of a Y52 sharp-cut filter pumped by a mid-IR pulse and probed by a visible pulse (546 nm).
(a) IR-pump-visible-probe signals of quinizarin in (, 0.2 mm cell) at two probe wavelengths. Polarization of the probe pulse was set parallel to the pump IR pulse. The inset shows the oscillatory components of the transient signals. (b) Fourier transform amplitude spectra of oscillatory components at two probe wavelengths. The asterisks designate solvent bands.
Low-frequency totally symmetric vibrational modes calculated with method. The symmetric OH-stretching mode having the dominant IR intensity around region is also shown . Vibrational frequencies are not scaled.
Change in (a) the force constant and (b) the dipole derivative of the OH-stretching mode with respect to the hydrogen-bond modulating motion.
Potential diagrams of the OH-stretching vibrational levels in the presence of (a) mechanical and (b) electrical anharmonic couplings with the low-frequency hydrogen-bond modulating vibrational coordinate (horizontal axis).
Results of the anharmonic vibrational analysis of quinizarin derived from DFT calculation.
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